SEED: An Operational Numerical Tool for Dosimetric Reconstruction in Case of External Radiological Overexposure

In the event of a radiological accident involving external exposure of one or more victims and potential high doses, it is essential to know the dose distribution within the body in order to sort the victims according to the severity of the irradiation and then to take them to the most suitable medical facilities. However, there are currently few techniques that can be rapidly deployed on field and capable of characterizing an irradiation. Therefore, a numerical simulation tool has been designed. It can be implemented by a doctor/physicist pairing, projected within a limited time as close as possible to the irradiation accident and emergency response teams. Called SEED (Simulation of External Exposures & Dosimetry), this tool (dedicated to dose reconstruction in case of external exposure) allows a rapid modeling of the irradiation scene and a visual exchange with the victims and witnesses of the event. The user can navigate in three dimensions in the accident scene thanks to a graphical user interface including a "first person" camera. To validate the performance of the SEED tool, two dosimetric benchmarking exercises were performed. The first consisted in comparing the dose value provided by SEED to that given by a reference calculation code: MCNPX. The purpose of the second validation was to perform an experiment irradiating a physical dummy equipped with dosimeters and to reconstruct this irradiation using SEED. These two validation protocols have shown satisfactory results with mean difference less than 2% and 12% for the first and second exercises, respectively. They confirm that this new tool is able to provide useful information to medical teams in charge of dosimetric triage in case of a major external exposure event.